1. Field of the Invention
This invention relates to a recording position adjusting pattern forming method, an image recording position adjusting method and an image recording apparatus, and more particularly relates to a recording position adjusting pattern forming method, an image recording position adjusting method and an image recording apparatus to be used for correction of the image displacement due to the recording position displacement between plural recording heads of an image recording apparatus on which plural recording heads are mounted.
2. Description of the Related Art
The mechanical fixing error of the fix position and fix attitude of heads that are arranged in parallel on a carriage causes the inclined printing of horizontal rules due to the printing position displacement between the heads and displacement of fixed angle to the scanning direction of a carriage.
To correct the printing position, the electric delay is properly applied to the printing signal that is applied to the heads so as to offset the error due to mechanical fixing or printing characteristic difference between the heads. Thereby, it is possible to correct the printing position.
At that time, for checking the proper adjustment magnitude of the electric delay, the delay detection is checked visually or automatically by means of an optical detection unit by use of a test pattern that is printed with a predetermined successive displacement of the electric delay to thereby detect the displacement magnitude of the parallel pattern included in the pattern or to detect the average density of the pattern. As the result, it is possible to correct the printing position properly.
Various methods for detection and correction of the fixing angle to the recording head (inclination of a head) and the printing position have been proposed. For example, Japanese Published Unexamined Patent Application No. Hei 11-99643 discloses a method in which a predetermined pattern is recorded by use of respective right and left heads to detect the printing position displacement between plural recording heads. At that time, the pattern of the one head is recorded with displacement of a predetermined magnitude and without displacement, the recorded result of the pattern is read by use of a sensor and the density of the pattern is compared to detect the recording position displacement.
For example, Japanese Published Unexamined Patent Application No. Hei 7-17076 discloses a technical method as a pattern to detect printing displacement in which an adjusting pattern having plural vertical rules of at least three lines, the relative position of which three lines is slightly displaced in the carrier scanning direction of the lines of the odd number line and the even number line, is printed, and the coincidence of the vertical rule on two lines and the coincidence of the vertical rule on three or more lines that form an approximate straight line with the whole vertical line is identified visually, the inclination of the printing is calculated, and the inclination is adjusted.
For example, Japanese Published Examined Utility Model Hei 3-8448 and U.S. Pat. No. 4,878,063 disclose the adjusting pattern of the horizontal line for visual adjustment, and furthermore the Japanese Published Unexamined Patent Application No. Hei 10-264485 discloses a method in which parallel line pattern is used as the adjusting pattern for visual adjustment.
Furthermore, for example, Japanese Published Unexamined Patent Application No. Hei 7-178964 and Japanese Published Unexamined Patent Application No. Hei 8-90835 disclose the printing pattern and a recording apparatus for adjusting the printing position of a reciprocal recording head.
In the case where a detection pattern is formed with a color monochrome and, in particular, the average density of the pattern is detected automatically by use of an optical unit, the sensitivity of C (cyan) or Y (yellow) is not sufficient due to the spectral characteristics of the optical detection unit, it is difficult to detect the density difference of the monochrome pattern, and a light source having the different spectral characteristics is required.
The parallel pattern is displaced by a predetermined magnitude from the proper value because of the structure of the pattern, a space appears on the pattern, and the average density is lowered. According to the method described hereinabove, though the density difference can be detected, the patterns (parallel bars) overlap each other in the magnitude equal to the caused space. Because the lower density color (low sensitivity) results in the higher density of the overlap area, the caused space and the density increase of the overlap area are offset each other to prevent the detection of the average density difference.
Because the density absolute value of the monochrome pattern is low (that is, the reflectance is high), in the case where the luminance of a light source is increased to enlarge the density difference, the output of a light receiving element is saturated and the luminance cannot be increased resultantly.
In the case of visual detection, the density difference or pattern displacement of Y is difficult to be recognized.
The present invention has been accomplished to solve the above-mentioned problem, and provides a method for forming recording position adjusting pattern, and an image recording position adjusting method and an image recording apparatus that are capable of correction of the recording position correct precisely.